1. Field Of The Invention
The present invention generally appertains to new and novel improvements in connections between tractor vehicles and trailers of any type or nature and especially relates to a new and novel coupling arrangement for preventing jack-knifing in such types of articulated vehicle assemblies.
2. State Of The Prior Art
In the operation of articulated vehicles, which essentially comprise a load-carrying trailer attached to a tractor vehicle by a fifth wheel coupling, a well recognized hazard is the tendency of the trailer to jack-knife during deceleration of the tractor vehicle or on slippery road surfaces. Jack-knifing usually occurs whenever the rear surface engaging wheels of the tractor vehicle becomes locked and skid in a direction normal to the direction of travel whereby the load carrying trailer swings about the fifth wheel coupling and tends to overtake the tractor vehicle.
In one type of jack-knifing condition, the front wheels of the trailer vehicle also lock and skid and the entire vehicle tends to skid in a straight line provided the tires of the trailer vehicle have similar frictional coefficients with the road surface. As the speed drops, any slight lack of balance between the frictional coefficients becomes more noticeable and the tractor vehicle starts to swing slowly but uncontrollably into a fully jack-knifed position.
In a second jack-knifing condition, the front wheels of the tractor vehicle do not skid and the slightest side force applied to such wheels will cause a sudden and most serious jack-knifing which is extremely difficult if not impossible to correct.
In the aforestated patent application, an anti jack-knifing device of a simple and most efficient structural and operational nature is disclosed.
Such device essentially comprises a turntable mounted on the tractor vehicle for rotation about a substantially vertical axis intersecting the longitudinal center line of the vehicle with a brake member carried by the turntable for rotation therewith and having opposing horizontal parallel faces defining brake surfaces. A fifth wheel coupling is secured to the turntable for rotation therewith and means is provided for connecting the trailer to the fifth wheel coupling so that the trailer is fast with the turntable for rotation therewith.
Brake callipers are mounted on the tractor vehicle so that they are restrained from movement about the aforestated vertical axis of rotation of the turntable. Such brake callipers are positioned for operational engagement with the brake surfaces at all articulated positions of the trailer relative to the tractor vehicle. The brake callipers are connected by suitable hoses to the fluid operated brake system of the trailer vehicle or can be connected to a dependent fluid system operated by a servo-cylinder actuated by the braking system of the trailer vehicle.
Whenever the wheel of the trailer vehicle are braked, the brake callipers will grip the brake surfaces and prevent articulation of the trailer relative to the tractor vehicle. The degree of braking torque applied to the brake surfaces by the brake callipers will depend upon the braking force applied to the wheels of the trailer vehicle so that the force applied by such brake callipers to prevent the trailer from jack-knifing will increase progressively with the deceleration of the entire articulated vehicle and with the transverse forces imposed on the trailer.
Such device has proven most effective in actual operation to inhibit or prevent jack-knifing. However, one point of improvement has been found to exist in protectively covering the brake member and the brake callipers so that they are not exposed to the rain and like elements.
Another point of improvement has been found to reside in lessening the overall weight of the device and simplifying the construction thereof, having regard to the mounting of the turntable on the tractor vehicle.